Method of making formates and formic acid.



UNITED s ATEs- PATENT curios.

HENRY HCIWARD, 0F BROOKLINE, MASSACHUSETTS.

METHOD OF MAKING FORMATES AND FORMIC ACID.

To all whom it may conm'n:

Be it known that I, HENRY HOWARD, a citizen of the United States,residing at Brookline, in the county of Suffolk and State ofMassachusetts, have invented certain new and useful Improvements inMethods of Making Formates and F ormic Acid,

of which the llowing is a specification.

In the manufacture of sodium formate by reaction between caustic sodaand carbon monoxid, it has been heretofore proposed to mix with thecaustic soda an inert material such as charcoal, coke or lime, with theobject of increasing the surface ex osed to the gas. This result isaccomplis ed in two ways; in the first lace the melting point of themixture is hig ier than the melting point of pure sodium hydroxid, thuspermitting the mass to be maintained in a pulverulent state under theconditions of temperature existi during the absorption of carbonmonoxld; and in the second place, an increased surface is exposed. duesimply to theincrease in bulk of the mass after addition of the inertfiller. The above materials are however highly objectionable inpractice, as they contaminate and interfere with the usefulness of thesodium sulfate which remains as a by-product in the treatment of theformate with sulfuric acid for the production of formic acid.

According to the present invention I use as a fillin material or inertbody to be mixed wit caustic alkali whichwis to be converted intoformate, the alkali metal salt which will constitute the residue of theoperation or the solid final roduct thereof, such salt possessing the avantage that it serves effectively during the operation to increase thesurface exposed to the gas and does not introduce an impurity into thefinal product.

In racticing the invention, sodium sulfate may e mixed with or incororated in the caustic'alkali in any approve manner. For instance causticsoda and sodium sulfate in proper roportions may beground together in ami 1, or the finely ound compounds may be intimately mixed in an apropriate apparatus: or caustic soda an so ium sulfate may be mixed insolution or in presence of water and the mass dried by eva ration; orthe caustic soda may be me ted, the sodium sulfate incorporatedbystirring, and the mass permitted to solidify. The resultmg mass issubjected to the action of car- Speciflcation 01' Letters Patent.

Io Drawing. Application filed June 10, 1908, Serial No. 437,676. RenewedAugust 8, 1910. Serial No. 576,077.

Patented Sept. 20, 1910.

bon monoxid at suitable temperatures and )ressures as is well understoodin the art or the production of sodium for-mate which is thereafterdecomposed by means of sulfuric acid,-leaving a residue consistinentirely of sodimn sulfate "Portions 0 this residue may be mixed withcaustic soda for the further practice of the method. Instead of usingsodium sulfate I may employ an alkali metal chlorid in case hydrochloricacid is .to be usedto decompose the formate. Or the formate may bedecomposed by phosphoric acid, yielding sodium phosphate, in which casesodium hosphate in solid form is employed as the inert body or fillerfor the caustic alkali. Similarly other alkali metal salts may beemployed, the formate being subsequently decomposed by the acid wlnchenters into the constitution of the salt used, whereby a residualproduct consisting of a single salt in marketable form is produced.

I claim:

1. The method of making formic acid which consists in mixing an alkalimetal hydroxid with the alkali metal salt which is to constitute thesolid residue of the operation, subjecting the mixture to the action ofcarbon monoxid under suitable conditions to produce formate, anddecomposing the formate by the acid which enters hit) the constitutionof the alkali metal salt mixed with the hydroxid.

2. The method of making formates which consists in mixing an alkah metalhydroxid and sulfate, and subjecting the mixture to the action ofcarbon. Il'lOIlOXld under suitable conditions to produce formate.

3'. The method of making sodium format-e which consists in mixin causticsoda and sodium sulfate, and subjecting the mixture to the action-ofcarbon monoxid under suitable conditions to roduce sodium formate. 4.The method 0 making formic acid'and sodium sulfate whichconslsts inmixing an alkali metal hydroxid and sulfate, subjecting the mixture tothe action of carbon monoxid under suitable conditions to produceformate, and decomposing the formate by sulfuric acid.

In testimony whereof, I aifix my signature in presence of two witnesses.

- HENRY HOWARD.

Witnessesz' ALBERT CHAMPION GILBERT, Ronaa'r JOSHUA KING.

